The NEW Build Your Own Arcade Controls
Main => Everything Else => Topic started by: tommy on December 26, 2007, 12:57:32 am
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I was experimenting with my Half-Life 2 server dll files and found I could change quite a few things if you know what to look for and I was able to customize my server more than I ever thought without writing a plugin for it.
Is there any use for this in Mame and Emulators? I would imagine I couldn't do anything very drastic to these files but it may still be able to change a few things.
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I think that's how the cheat system works in it, but i'm not 100 percent sure.
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You should be able to edit things like # of lives, and text, but you have to know where to look. And if the ROM's programming contains checksum checks, then chances are any mod won't run.
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...unless you run a checksum on the newly modded image and then insert that checksum into the verification using the same hex editing method.
That's a lot of effort for minimal results. You'd probably be better off trying to disassemble the code and doing it that way if you can find the right disassembler and compiler.
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I was experimenting with my Half-Life 2 server dll files and found I could change quite a few things if you know what to look for and I was able to customize my server more than I ever thought without writing a plugin for it.
Is there any use for this in Mame and Emulators? I would imagine I couldn't do anything very drastic to these files but it may still be able to change a few things.
I would say there is zero use for that kind of thing for Mame because you have the source code. For closed-source emulators, maybe there might be some use for hex editing but it would easier to modify Mame to do what you want.
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I assume he's talking about altering ROM images and not MAME itself, mostly because you're right, the source is available and so a hex editor is irrelevant.
That may be a bad assumption on my part.
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The cheat system in Mame works by monitoring memory locations known to be home to key game information, such as the number of lives left or whatever.
If you want to modify the actual game to display "Tommy XYZ" instead of "Game Over", rather than modifying the emulator, that is doable with a hex editor subject to the checksum restrictions Ray mentioned.
More complicated still is the new Donkey Kong code which implements new levels using the existing sprites.
I personally would like to extend Galaga to include "tripleship" support and a screen saver. That would be a fun project, and it would be super cool to load those roms into my Galaga machine at home.
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Also, if your ROMs have some type of encryption/compression in there, which most ROMs typically do, it's not an easy "read this and change that" type of change.